No broad-based international agreement on sharing rivers currently exists, even though much of the world depends on water from rivers that flow through more than one nation. But that may be about to change, as two separate global river treaties are close to being approved.

Is peace about to break out on the world’s rivers?

It is amazing that until now there has been no global agreement on sharing international rivers. From the Mekong to the Jordan and the Niger to the Euphrates, there has been nothing to stop upstream countries from building giant dams that cut off all flows downstream. Yet in the coming weeks we could have two such treaties.

First, the continuing bad news: Belligerent countries are still exerting their hydrological muscle. Just this month, Laos began construction of the first dam on the main stem of the lower Mekong River in Southeast Asia. It hopes that the Xayaburi dam will help it become the region’s hydroelectric powerhouse.

On the upper Mekong, China has already built four giant dams, including one taller than the Eiffel Tower. These dams are all being constructed without the approval of downstream neighbors, including the 60 million people in Cambodia and Vietnam who fear the barriers will block fish migration and deprive them of fertile silt for their rice fields.

Meanwhile in Africa, Ethiopia last year began work on the Renaissance Dam on the Nile, which will be the largest hydroelectric dam in Africa. Again, downstream nations Egypt and Sudan had no say. And in the Middle East, fears grow that Turkey could use its control of the Euphrates as a weapon in any future border conflict with war-torn Syria, a downstream nation that is heavily dependent on the river.

More than 40 percent of the world’s people live in 263 river basins that straddle international borders. The Danube, Rhine, Congo, Nile, Niger, and Zambezi rivers all pass through nine or more countries. Transboundary rivers contain 60 percent of the world’s river flows — for two-thirds of them, there are no agreements on water sharing.

This is dangerous. Guinea threatens to barricade the River Niger, which could dry out the inner Niger delta, a wetland jewel on the edge of the Sahara in neighboring Mali. In September, Vladimir Putin visited the mountain states of Tajikistan and Kyrgyzstan in Central Asia, where he announced financial backing for more dams on the Amu Darya and Syr Darya rivers to generate hydropower in those countries. But he ignored opposition from downstream Uzbekistan and Kazakhstan who fear the dams will deprive them of summer flows to irrigate their cotton crops.

Water is today the most important global resource that does not have any international agreement, says World Bank lawyer Salman M.A. Salman. Abstractions of water from rivers have tripled in the past 50 years, mostly for irrigation. The entire flows of some rivers are now being taken for human use. And the natural flows of many others are disrupted by hydroelectric dams that only allow water to pass when the dam owners want electricity.

What treaties there are, often date back to colonial times. In international law, the Nile is governed by deals drawn up by the British in 1929 and 1959, which give all the water to downstream Egypt and Sudan and none to the eight upstream nations. Those laws are discredited, and in 2010, six upstream nations led by Ethiopia reached their own accord — a treaty that Egypt and Sudan have not joined.

Back in 1997, the UN adopted the Convention on the Non-Navigable Uses of International Watercourses. It did not lay down hard and fast rules for sharing waters, but it was a statement of principle that nations should ensure the “sustainable and equitable use of shared rivers.”

Only three countries voted against: China, Turkey and Burundi — all of them upstream countries on major rivers. China is the water tower of Asia. Its Tibetan plateau is the source of the Indus, Brahmaputra, Irrawaddy, Salween, and Mekong rivers. But in refusing to sign the treaty, China asserted that it had “indisputable territorial sovereignty over those parts of international watercourses that flow through its territory.”

To come into force, the treaty required 35 nations to ratify it in their legislatures. To date only 28 countries have done so. Other refuseniks include the U.S. and Britain, an original sponsor of the treaty. But the momentum for ratification is picking up. Eight of the 28 ratifiers did so in the last three years. France has become a cheerleader for the convention. Jean-Pierre Thebault, France’s environment ambassador, told a meeting I attended in Helsinki in September that he hoped enough nations would join for it to come into force in time for the UN’s International Year of Water Cooperation in 2013.

Meanwhile the treaty has a counterpart: the Helsinki convention. This began as a 1992 deal on river cooperation between European nations under the UN Economic Commission for Europe. But at a meeting in Rome set for Nov. 28-30, its members are likely to vote to allow any nation to join. Early potential signatories include Iraq and Tunisia.

France’s Thebault says the two treaties could complement each other. For while the 1992 treaty is a statement of principle about water sharing, the Helsinki convention is “bolder,” with formal arrangements for drawing up deals.

The Rome meeting of the Helsinki convention is also likely to extend its purview to drawing up rules for sharing underground water reserves. It could, for instance, help save the ancient water beneath Jordan and Saudi Arabia, which the two countries are currently racing to pump out before the other does. Likewise, it could manage the Nubian aquifer beneath Libya, Egypt, Sudan and Chad, which is currently being tapped by Libya; and the Guarani aquifer that straddles the borders between Brazil, Paraguay, Uruguay and Argentina.

Whether global governance of water can help the aquatic environment is another matter. WWF, which has lobbied for countries to ratify the UN treaty, wants future river deals to keep some water as “environmental flows” to maintain freshwater fisheries and wetlands. But the danger is that the opposite could happen. If downstream nations are more confident of how much water will reach them, they may build more dams to capture it.

This has happened on the Indus River, where a 1960 treaty brokered by the World Bank shared out the river and its tributaries between upstream India and downstream Pakistan. The result has been more dams and an ecological disaster downstream. The Indus dries up for months at a time, the coastline is retreating, its giant delta is peppered with dead mangroves, and salty seawater has invaded farms.

But hopes are nonetheless high that greater sharing of the world’s rivers could be imminent. David Grey, a water policy expert formerly with the World Bank and now at Oxford University, says there is growing recognition of the need for global oversight of the world’s water. He says it could, at the least, end the habitual hydrological secrecy of many upstream nations, who treat river flow data as state secrets.

Speaking in Vienna last month, Grey pointed out that India rarely tells Bangladesh what flows are coming down the Ganges. The result is disruption to farming and unnecessary damage and deaths from flooding. Likewise, he believes better sharing of Nile flow could assuage Egyptian fears about the capacity of upstream dams on the Nile to cut off its vital supplies. But in reality, Grey said, there is so much water in the Nile that “you could take as much water out of the river in east Africa as you want, and Egypt would never notice the difference.”

Water peacemakers argue that sharing water isn’t necessarily a zero-sum game. Both sides can gain. In recent weeks, authorities in the U.S. and Mexico have carved out a new agreement on sharing the Colorado River, which irrigates much of the arid Southwest before passing over the border into Mexico and delivering a tiny saline trickle through its desiccated delta into the Gulf of California.

An existing treaty, signed in 1944, is very one-sided, giving Mexico the right to only a tiny amount of the flow, which Mexico finds it difficult to use because it has few storage structures and because many irrigation canals were damaged in an earthquake. Under the new deal — which has been approved by U.S. regional authorities and awaits federal sign-off — Mexico would be able to store some of its water allocation in Lake Mead, the huge U.S. storage reservoir on the river in Nevada and Arizona. Meanwhile, U.S. water authorities will be allowed to invest in lining irrigation canals across the border in Mexico to save water. Those authorities will then be entitled to keep back the equivalent amount of water on the American side of the border and use it for their own purposes.

With this arrangement, everybody gets more water. There might even, U.S. regulators hint, be more left for the Colorado’s dried-out delta. It is an optimistic sign of how water peace could take hold — and one worth clinging to, amid the wreckage of the current hydrological anarchy on the world’s rivers.